The present invention relates generally to workplace personnel fall arresters of the retractable lifeline type and more particularly to a combined personal fall arrester and emergency retrieval apparatus capable of arresting a person's fall from a height, suspending the person after fall arrest, and thereafter capable of assisted retrieval of the suspended fallen person by raising or lowering him to a selected position within the apparatus' range to facilitate rescue. The apparatus is capable of being selectively used as either a fall arrester only with back-up emergency retrieval capability or an emergency retrieval device with back-up fall arrester capability that can be used to retrieve several persons, one at a time, without necessarily depending on self-assistance of the person or persons being retrieved. The present invention also generally relates to means of anchoring and rigging the fall arrester and emergency retrieval apparatus and more particularly to portable tripod anchorage means for mounting the apparatus.
Fall arresters of various types have long been in use in working environments in which a worker is exposed to the hazard of falling from a height. Fall arresters, of the retractable lifeline type dealt with herein, typically comprise a clutch-brake type cable drum mounted within a housing. The fall arrester is attached to an anchorage, usually a fixed structural member, and the free end of a cable, which is wound about the cable drum, is attached to a body harness worn by the worker. The cable drum is generally biased in the direction of rotation opposite to that in which the cable is payed out to prevent slack from developing in the cable as the worker descends or ascends. A clutch-brake type cable drum has the design characteristic that when the speed at which the cable is payed out reaches a predetermined value, the rotation of the cable drum is braked to a halt at a predetermined deceleration rate. The rate of deceleration is set to brake the fall relatively quickly yet not so rapidly as to give rise to high decelerative forces being applied to the falling person. After braking, the cable drum is restrained from rotation until the downward load on the cable is removed.
Thus, if a worker attached to a fall arrester cable falls from a supported position, his fall is arrested as soon as his fall velocity causes the cable drum to reach a predetermined rotational speed. Subsequent to the fall and fall arrest, the fall victim is suspended by the cable at a fixed elevation. If the fall victim is unconscious, injured or otherwise physically unable to grasp a nearby structure, such as a ladder or the like, to regain a supported position, he must rely on others to remove him from his suspended position. Raising or lowering a fall victim can be very difficult, such as in egress from confined spaces where a worker has descended through a manhole. Typically, other persons above the fall victim, where the fall arrester is mounted, lower another line and the fall victim attaches it to his harness whereupon the persons above raise him from his suspended position. If the fall victim is helpless, it is generally necessary for another person to descend or be lowered to the fall victim to attach a rescue line to his harness. Another method of rescue is for those who are at the elevated position to simply haul in the fall arrester cable in a hand-over-hand manner to raise the fall victim. In some applications such as where overhanging objects are present which would interfere with the fall victim's ascent or where the fall victim is suspended a few feet above a lower base surface, it is desirable to lower the victim rather than raise him from the suspended position. In this case, it is necessary to first raise the fall arrester cable a slight amount to remove the load on the cable drum and then to slowly lower the worker, again in a hand-over-hand manner or with the aid of a second line, until the worker reaches the lower support surface. Raising or lowering a fallen worker from a suspended position at the end of the fall arrester cable thus usually requires the services of several people and can be very hazardous, awkward and time-consuming.